1. Field of the Invention
The present invention relates to an elastic wave device in which a longitudinally coupled resonator elastic wave filter is provided on a piezoelectric substrate.
2. Description of the Related Art
In an elastic wave device described in WO 2010/150882, interdigital transducer (IDT) electrodes and a ground-side wiring line are disposed on a piezoelectric substrate. The ground-side wiring line surrounds the IDT electrodes. A hot-side wiring line, which is connected to one of the IDT electrodes, three-dimensionally crosses the ground-side wiring line with an insulating film interposed therebetween.
In WO 2014/199674, a ground-side wiring line, which connects two longitudinally coupled resonator elastic wave elements to each other, and a hot-side wiring line, which connects another two longitudinally coupled resonator elastic wave elements to each other, cross each other with an insulating film interposed therebetween. In Japanese Unexamined Patent Application Publication No. 2004-282707, wiring lines that have different potentials cross each other with an insulating film interposed therebetween.
In elastic wave devices of the related art such as those described in WO 2010/150882, WO 2014/199674, and Japanese Unexamined Patent Application Publication No. 2004-282707, a three-dimensional crossing portion is provided in a portion spaced apart from the IDT electrodes. Consequently, the area of a piezoelectric substrate surface inevitably increases, and it is difficult to reduce the sizes of such elastic wave devices.